Amy Iezzoni, a fruit breeder at Michigan State University, traveled to Eastern Europe and the countries of the former Soviet Union to collect many different types of cherry trees.

Dan CharlesNPR

Some fruits, like apples, you can find anywhere. But others have gotten a little bit lost in today's global food business.

Take tart cherries, also known as sour cherries. Unlike sweet cherries, America's tart cherries are too fragile to ship very far, so most people never get to taste a fresh one.

They're typically frozen, then baked into that iconic American dessert, the cherry pie — and cherry pies aren't as popular as they used to be.

Yet the humble sour cherry is experiencing an unlikely renaissance — and the best may be yet to come.

The revival is partly based on the fruit's growing reputation as a nutrient-packed superfood. There are studies — many paid for, it must be noted, by the Cherry Marketing Institute — showing that this delicacy, with its addictive counterpoint of tangy and sour, can help reduce insomnia, or pain in joints and muscles.

Mitchell Seymour, a researcher at the University of Michigan Medical School, fed tart cherries to rats. "We saw significant reductions in things like inflammation in the animals. We saw some improved insulin resistance," he says.

"I think it's exciting!" Seymour continues. "I think it's a good product, and it's nice to know that a majority of that product is produced in my home state of Michigan."

In fact, the western edge of his home state, along the shores of Lake Michigan, grows about three-quarters of the country's supply of tart cherries.

They do, at least, in a good year. But last year was a disaster, perhaps the worst in memory. An early spring caused the trees to blossom, and then, on March 23, a blast of cold air arrived.

Mike Van Agtmael, a cherry farmer in the town of Hart, stayed up all night, watching the thermometer. "It got to about 3:30 a.m., and the temperature started dropping. It didn't matter what we did, it just kept dropping and dropping," he says.

The blossoms froze. The crop was ruined.

Now, there's a reason why all those trees bloomed and froze in unison. The vast majority of tart cherry trees in the U.S. are genetically identical.

But they don't have to be. And this is where we get to the second part of the tart cherry renaissance.

In the tart cherry's ancestral homeland of Eastern Europe, there's a world of cherry diversity. It could help avoid weather disasters like the freeze of 2012, and it could also bring a wealth of new tart cherry flavors to the United States.

One scientist, Amy Iezzoni of Michigan State University, is bringing some of that diversity to the United States.

Iezzoni is the country's one and only tart cherry breeder, and she's passionate about her mission. "Somebody needs to do this!" she exclaims at one point, as she shows me around her orchard.

On this day, she's in a hurry. Her tart cherry trees are blooming, ready for pollination.

When she took this job in 1981, she barely knew where to start. The only tart cherry trees she could find were from America's standard commercial variety, called Montmorency.

But a cherry breeder needs different kinds of cherry trees to make genetic crosses, carefully fertilizing the flowers of one tree with pollen from another, reshuffling genes and creating new combinations.

A plant breeder with just one variety is like a painter with only one color.

"I got to see Montmorency, Montmorency, Montmorency," Iezzoni recalls. "OK, spring comes. What am I going to cross it with? I have nothing! Well, I should go to Eastern Europe! And can I get there and back before my bloom? I could. I did it."

This was during the Cold War; an iron curtain stood between her and those tart cherry varieties.

But Iezzoni got official permission to cross through it, and she followed the tart cherry bloom northward across Europe, from Yugoslavia to Poland. She collected pollen all the way, and brought it back to fertilize blossoms in Michigan.

Along the way, she also got a taste of a whole different tart cherry culture. In Hungary, for instance, sour cherry trees line village streets. "Their tart cherries are so good, they eat them fresh. I have actually seen in Hungary the price of tart cherries higher than sweet cherries," Iezzoni says.

More trips followed. Today, 30 years later, Iezzoni's breeding orchard is a spectacular exhibition of the tart cherry's family tree.

There are short bushes and tall trees. Perhaps most interesting: There are trees that weren't bothered by last spring's late freeze. Iezzoni points to one, named Tamaris, which she got from a research institute in Michurinsk, Russia.

It's a modest little tree. It stands out because it has almost no blossoms. "Montmorency has pretty much finished blooming, and this thing just sits there. Sits there. Sits there," Iezzoni says.

Last year, being a late bloomer was a huge advantage. This tree didn't bloom, along with the others, during that warm spell, so there were no blossoms to freeze when the cold air blew through. It bloomed later, and produced its normal crop of cherries.

Now, those cherries aren't very good, so Iezzoni is doing more cross-pollinating, mating this tree with others that do make nice cherries, collecting the seeds, and planting that next generation.

Right now, she's waiting anxiously to collect pollen from some of that next generation — especially the little trees that are blooming really late.

What she hopes to create, eventually, is a late-blooming tart cherry tree that yields a big crop of great-tasting cherries.

It's just a part of her bigger project — introducing more variety into the tart cherry landscape: different types of trees, and flavors, that might even change the image and culture of tart cherries in America.

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

Transcript

ROBERT SIEGEL, HOST:

From NPR News, this is ALL THINGS CONSIDERED. I'm Robert Siegel.

MELISSA BLOCK, HOST:

And I'm Melissa Block. You can find some fruits like apples in just about any grocery store in the country, but other fruits have gotten a bit lost in today's food business. Unlike their sweet counterparts, sour cherries are too fragile to ship far and that means most people never get to taste a fresh one. Instead, they end up in that iconic American dessert, the cherry pie.

Well, today, we can report that the humble sour cherry is in the middle of an unlikely renaissance. NPR's Dan Charles explains.

DAN CHARLES, BYLINE: Tart cherry juice is now showing up in health food stores as a nutrient-packed superfood. There are studies, many paid for, it must be noted, by the Cherry Marketing Institute, showing that this sour-sweet fruit can help reduce insomnia, or pain in joints and muscles. Researcher Mitchell Seymour, at the University of Michigan Medical School, fed tart cherries to rats.

MITCHELL SEYMOUR: And we saw significant reductions in things like inflammation in the animals. We saw some improved insulin resistance.

CHARLES: If all this research gives the tart cherry business a boost, Seymour is happy to see it.

SEYMOUR: I think it's exciting. I think it's a good product, and it's nice to know that a majority of that product is produced in my home state of Michigan.

CHARLES: In fact, the western edge of his home state, along the shores of Lake Michigan, grows something like three-quarters of the country's sour cherries, with their addicting counterpoint of tangy and sweet, perfect for baking. And this year, the orchards are looking great. Mike Van Agtmael's farm near the town of Hart is a sea of white blossoms shimmering in the sunlight.

MIKE VAN AGTMAEL: I mean, how's it get any better than this out here today? There's nothing I'd rather be growing than tart cherries and apples, you know. That's what I told my wife. If I was to die tomorrow, you know, there's nothing that I could ask for, even after going through a year like we did last year.

CHARLES: Last year was no good at all. It started with a deceptively mild spring.

AGTMAEL: It got to about 3:30 and temperature started dropping. And it didn't matter what we did, it just kept dropping and dropping.

CHARLES: The blossoms froze. The crop was ruined. Now, there's a reason why all those trees bloomed and froze in unison. The vast majority of tart cherry trees in the U.S. are genetically identical. But they don't have to be. There's a world of different kinds of tart cherries out there in their homeland of Eastern Europe.

And one scientist, Amy Iezzoni at Michigan State University, is bringing some of that diversity to the United States.

AMY IEZZONI: Somebody needs to do this.

CHARLES: Iezzoni is in a hurry. She has to be this time of year. Her tart cherry trees are blooming, ready for pollination. Iezzoni reaches for a blossom and suddenly her hands slow down. She gently pulls away part of the flower, the pollen-producing part. She throws that away. She wants to fertilize this flower with pollen from another tree.

IEZZONI: Did you see how that worked? This is how we prepare the branch for pollen.

CHARLES: Iezzoni is the country's one and only tart cherry breeder. When she took this job in 1981, she wasn't exactly sure where to start. The only tart cherries she could find were from America's standard commercial variety, Montmorency. But a cherry breeder needs different kinds of cherry trees to make those genetic crosses, reshuffling the genes and creating new combinations.

A plant breeder with just one variety is like a painter with only one color.

IEZZONI: I got to see Montmorency, and Montmorency, and Montmorency. OK, spring comes. What am I going to cross it with? I have nothing. Well, I should go to Eastern Europe. And can I get there and back before my bloom? And I could. I did it.

CHARLES: This was during the Cold War; an iron curtain stood between her and those tart cherry varieties. But Iezzoni got official permission to cross through it, and she followed the tart cherry bloom northward across Europe, from Yugoslavia to Poland. She collected pollen all the way and brought it back to fertilize blossoms in Michigan.

Along the way, she also got a taste of a whole different tart cherry culture. In Hungary, for instance, tart cherry trees line village streets.

IEZZONI: Their tart cherries are so good, they eat them fresh. And I actually have seen in Hungary the price of tart cherries higher than sweet cherries.

CHARLES: More trips followed. Today, 30 years later, Iezzoni's breeding orchard is a spectacular exhibition of the tart cherry's family tree. There are short bushes and tall trees. Perhaps most interesting right now, there are trees that were not bothered by last spring's freeze.

IEZZONI: This is Tamaris, from Michurinsk, Russia.

CHARLES: It's a modest little tree. It stands out because it's a really late bloomer.

CHARLES: Last year, this tree didn't bloom during the warm early spring, so there were no blossoms to freeze during the cold snap. It bloomed later and produced its normal crop of cherries. Now, those cherries aren't very good, so Amy Iezzoni is doing more cross-pollinating, mating this tree with others that do make nice cherries, collecting the seeds, then planting them.

Right now, she's waiting to collect pollen from some of that next generation, especially the little trees that are blooming really late.

IEZZONI: See.

CHARLES: Little buds coming.

IEZZONI: Little flowers. Those are what we're anxiously waiting for.

CHARLES: What she hopes to get, eventually, is a late-blooming tart cherry tree that yields a big crop of great-tasting cherries. But this is just a part of her bigger project, introducing more variety into the tart cherry landscape, trees and flavors that might even change the image and culture of tart cherries in America. Dan Charles, NPR News. Transcript provided by NPR, Copyright NPR.